Generally, the present disclosure is related to the field of seals for seating rotary shafts. The methods and apparatus are particularly related to the field of unitary combination lip and sleeve seals. More specifically, the present invention relates to an improved seal adapted for use in severe duty applications where oil and grease must be held in contact with rotary shaft and bearing assemblies. The present invention incorporates design features that prevent the seal from wearing or cutting a groove into the associated rotary shaft, which can occur with other seals during normal operation.
The present seal structure yields a very important benefit over prior seal systems, in addition to providing most of the benefits of these seals. Previous seals, an example of which is shown in FIG. 1, have a tendency to cut or wear a circular groove into the associated rotary shaft. Theses grooves are primarily caused by the frictional contact between the faceplate wiper ring 189 and the shaft 121, as the shaft is rotated during normal operation of the machine. It is undesirable to have the wiper ring cutting a groove into the rotary shaft during operation because these grooves weaken the shaft and can eventually lead to cracking of the spindle. It is equally undesirable to remove the wiper ring from the seal faceplate, because the wiper ring provides an initial barrier against environmental contaminants. Therefore, the present invention alleviates the tendency of the wiper ring to cut or groove the rotary shaft, without compromising the overall seal quality.
These and further objects of the apparatus taught in accordance with this specification, the claims, and the appended drawing figures are set forth below.
The present disclosure, which incorporates herein by reference in their entirety, U.S. Pat. No. 6,186,507 to Oldenburg and application Ser. No. 09/401,570, filed Sep. 22, 1999, to Oldenburg, shows a retrofittable radial lip seal adapted to fit coaxially around, and reduce wear to, a circular rotatable shaft. In one embodiment, the seal comprises a first sleeve, a cylindrical seal case, a faceplate, a second sleeve and a flexible member. The first sleeve has an inner end that would normally be in contact with the grease, oil, or other fluid to be contained within a housing, an outer end opposite the inner end, a bore that has an elastomeric coating, and a first sleeve flange extending radially outward from the outer end of the first sleeve and generally perpendicular to the first sleeve axis. The first sleeve flange is terminated with an outer edge.
A cylindrically hollow seal case adapted for fitting into a bore is disposed coaxially around the first sleeve. The case is formed from a generally cylindrical case body having an outside surface, or outside diameter, that may be disposed in a bore and in contact with the wall of the bore. An elasotmeric coating may be affixed to the outside of the case body. By coating the outside of the metal case body with an elastomeric coating or layer, it is possible for the seal to securely fit a bore that may be worn or slightly damaged through use.
A case flange extends radially inwardly from, and generally perpendicular to, the longitudinal axis of the inside of the case. It is believed preferable to draw the case flange from the material of the case body. When formed in that manner, the material of the case body is doubled back on itself to yield two thicknesses of the case material for the distance between the case inner end and the case flange.
A generally planar circular faceplate has an inside surface, an outside surface, and a central aperture slightly larger than the outside diameter of the first sleeve. The plane of the inner faceplate surface is disposed generally parallel to the case skirt and the face of the first and second sleeve flanges. An elastomeric faceplate wiper ring, having at least one and preferably two main elastomeric excluding lips, can be attached to the faceplate at the central aperture so that the lips contact the outer surface of the second sleeve. The faceplate wiper ring has the ability to exclude contaminants from the remainder of the seal by contacting the second sleeve. In addition, the second sleeve and second sleeve elastomeric coating prevent the faceplate wiper ring from directly contacting the rotary shaft, and thereby prevent the wiper ring from wearing a groove into the rotary shaft during operation of the machine.
A second sleeve is located adjacent to the first sleeve and is adapted to fit coaxially around the shaft. The second sleeve has an outer end that is exposed to ambient conditions, an inner end adjacent to the outer end of the first sleeve, a bore that has an elastomeric coating, and a second sleeve flange that extends radially outward from the inner end of the second sleeve and runs generally perpendicular to the second sleeve axis. A circular elastomeric perimeter lip extends radially outwardly from the inner edge of the second sleeve flange to contact a generally cylindrical hollow seal case.
In another embodiment, the first sleeve and the second sleeve are replaced by one continuous sleeve that is adapted to fit coaxially around a shaft. In this embodiment, the seal comprises a continuous sleeve, a cylindrical seal case, a faceplate and a flexible member. The continuous sleeve has an inner end that extends into the sealed region and outer end that contacts the environment excluded by the seal. The continuous sleeve is operably positioned between the faceplate and the rotary shaft, thus preventing the wiper ring excluder lips from contacting the shaft.
In one embodiment, the seal is made into a unitary structure by inserting the first sleeve inner end through the case flange so that the first sleeve flange is positioned near the bumper. The second sleeve is then placed inside the seal case so that the perimeter lip of the second sleeve flange contacts the inside surface of the seal case outer end near the case skirt. All of the voids between the case inner flange and the case skirt can be packed with grease before final assembly of the seal. The faceplate is then attached to the case skirt thereby retaining the sleeves within the case portion. It has been found that a high quality water-resistant grease works well. One satisfactory grease is made by Esso Corporation and sold under the trade name xe2x80x9cBEACON 325,xe2x80x9d although other products may also serve quite satisfactorily. Although it is believed preferable to attach the faceplate to the case by crimping the peripheral edge of the faceplate around the outer edge of the case skirt, the faceplate may also be attached to the skirt by welding, brazing, adhesive bonding, or by any other of the usual means of connecting such items. It is desired that the junction between the case skirt and the faceplate be impervious to external contaminants and internal lubricants at the temperatures, pressures and other conditions in which the seal was operated.